Commit e5964689 authored by Bhaktipriya Shridhar's avatar Bhaktipriya Shridhar Committed by Mauro Carvalho Chehab

[media] gspca: jl2005bcd: Remove deprecated create_singlethread_workqueue

The workqueue "work_thread" is involved in streaming the camera data.
It has a single work item(&sd->work_struct) and hence doesn't require
ordering. Also, it is not being used on a memory reclaim path.
Hence, the singlethreaded workqueue has been replaced with the use of
system_wq.

System workqueues have been able to handle high level of concurrency
for a long time now and hence it's not required to have a singlethreaded
workqueue just to gain concurrency. Unlike a dedicated per-cpu workqueue
created with create_singlethread_workqueue(), system_wq allows multiple
work items to overlap executions even on the same CPU; however, a
per-cpu workqueue doesn't have any CPU locality or global ordering
guarantee unless the target CPU is explicitly specified and thus the
increase of local concurrency shouldn't make any difference.

Work item has been flushed in sd_stop0() to ensure that there are no
pending tasks while disconnecting the driver.
Signed-off-by: default avatarBhaktipriya Shridhar <bhaktipriya96@gmail.com>
Acked-by: default avatarTejun Heo <tj@kernel.org>
Signed-off-by: default avatarHans Verkuil <hans.verkuil@cisco.com>
Signed-off-by: default avatarMauro Carvalho Chehab <mchehab@s-opensource.com>
parent 95705083
...@@ -45,7 +45,6 @@ struct sd { ...@@ -45,7 +45,6 @@ struct sd {
const struct v4l2_pix_format *cap_mode; const struct v4l2_pix_format *cap_mode;
/* Driver stuff */ /* Driver stuff */
struct work_struct work_struct; struct work_struct work_struct;
struct workqueue_struct *work_thread;
u8 frame_brightness; u8 frame_brightness;
int block_size; /* block size of camera */ int block_size; /* block size of camera */
int vga; /* 1 if vga cam, 0 if cif cam */ int vga; /* 1 if vga cam, 0 if cif cam */
...@@ -477,9 +476,7 @@ static int sd_start(struct gspca_dev *gspca_dev) ...@@ -477,9 +476,7 @@ static int sd_start(struct gspca_dev *gspca_dev)
return -1; return -1;
} }
/* Start the workqueue function to do the streaming */ schedule_work(&sd->work_struct);
sd->work_thread = create_singlethread_workqueue(MODULE_NAME);
queue_work(sd->work_thread, &sd->work_struct);
return 0; return 0;
} }
...@@ -493,8 +490,7 @@ static void sd_stop0(struct gspca_dev *gspca_dev) ...@@ -493,8 +490,7 @@ static void sd_stop0(struct gspca_dev *gspca_dev)
/* wait for the work queue to terminate */ /* wait for the work queue to terminate */
mutex_unlock(&gspca_dev->usb_lock); mutex_unlock(&gspca_dev->usb_lock);
/* This waits for sq905c_dostream to finish */ /* This waits for sq905c_dostream to finish */
destroy_workqueue(dev->work_thread); flush_work(&dev->work_struct);
dev->work_thread = NULL;
mutex_lock(&gspca_dev->usb_lock); mutex_lock(&gspca_dev->usb_lock);
} }
......
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